The invention relates to apparatus for providing limited motion freedom for passengers wearing seat belts or shoulder harnesses in vehicles. This invention was disclosed under the Document Disclosure Program as of Aug. 16, 1982, Document No. 110431. The objectives of the invention in part are similar to those defined in applicant's prior U.S. Pat. No. 3,419,308, issued Dec. 31, 1968 and entitled "Limited Motion Device for Shouler Harness and the Like", and U.S. Pat. No. 3,588,173, issued June 28, 1971 entitled "Momentum Actuated Harness". Like each of the patented devices, the present application defines apparatus by which an occupant is afforded the protection of secure motion restraint when a large momentum change occurs while having limited freedom of movement under small changes of momentum while engaged with the restraint harness. While many devices have been proffered the driving public in the U.S. in the past two decades that are responsive to momentum changes, none, including the highly touted, unlamented, air bags, has been accepted by or popular with drivers and riders. Most such mechanisms have been too cumbersome when worn and generally not employed by passengers when installed in vehicles. Other devices have been too complicated to be built within the price range acceptable to industry or the buying public. One particular problem with existing seat belt restraints is that, above a predetermined force level, they are substantially unyielding. Accordingly the passenger may be injured by the high forces of his body against the fixed and substantially rigid restraining belt.
I have invented a momentum responsive latch for use with a restraint harness combining seat and shouler belts that is easy to use, occupies little space within the passenger compartment and is compatible with conventional harnesses now in use. The latch mechanism is simple to fabricate and install and needs little explanation for proper use by vehicle occupants. I have also discovered that, by providing an arrangement for permitting slight limited release of the restraining belt at very high force levels, injury to the passengers may be reduced, while still restraining the driver and passenger against impact against the dashboard, windshield or other parts of the vehicle.